KAMLOOPS, B.C. – Officials say unsettled weather could continue to pose challenges to efforts to contain the violent wildfires plaguing British Columbia.

Environment Canada says it expects scattered thunderstorms and strong winds gusting up to 70 km/h to develop across much of the central and southern Interior.

The fires have been threatening communities in the region for more than a week.

About 17,000 people had already fled their homes across the affected areas when an evacuation order was issued Saturday afternoon to the residents of the City of Williams Lake and numerous surrounding areas.

Many of Williams Lake's 11,000 residents had left voluntarily in recent days, but the order means thousands more are headed to safety in Kamloops and other cities.

Williams Lake was affected by the largest of seven evacuation orders issued Saturday.

Cariboo Regional District Chairman Al Richmond said winds began to pick up Saturday afternoon, prompting an expansion of evacuation alerts.

BC Wildfire Service said Saturday there are about 161 active wildfires in the province, 14 of which pose a direct threat to communities.